Unanticipated products from reductive and oxidative cleavages of 1‐substituted 3,3‐diphenyl‐1′‐methylspiro[azetidine‐2,3′‐indoline]‐2′,4‐diones

Titled spiroazetidinones 1a , 1b undergo reductive cleavage on treatment with excess lithium aluminum hydride forming 3‐benzhydryl‐1‐methylindole as the main product together with a γ‐amino alcohol depending upon the substituent present on the azetidin‐2‐one ring. Treatment of 1a with Ce(IV) ammonium nitrate affords 2‐hydroxy‐ N ‐(4‐methoxyphenyl)‐2,2‐diphenylacetamide besides the anticipated N ‐unsubstituted 2‐azetidinone, whereas a similar treatment of 1‐benzhydryl‐3,3‐diphenyl‐2‐azetidinone 1b affords the ring expansion product 1,3‐oxazolidin‐4‐one. The products have been characterized on the basis of satisfactory analytical and spectral (IR, 1 H and 13 C‐NMR, DEPT, HMBC) data and their formation is discussed. J. Heterocyclic Chem., (2011).